The present invention relates to a sawtooth wire for producing an all-steel sawtooth clothing for the doffer and/or doffing cylinder of a carding machine with a plurality of teeth successively arranged in the longitudinal direction of the wire. Each tooth has a tooth breast beginning at the tooth bottom and extending in the direction toward the tooth tip and a tooth back, which is connected with the tooth breast by two tooth flanks extending parallel to the longitudinal direction of the wire and which extends from the tooth tip in the direction of the following tooth bottom. The invention further relates to a method for producing sawtooth wires of this type.
A carding machine is used in the production of yarns for the purpose of aligning and cleaning the textile fibers that form the yarns. For this purpose, the textile fibers are supplied by means of a supply roller to a so-called swift. This is a cylindrical element whose cylindrical surface is provided with all-steel hook or sawtooth clothing and is rotated about the cylinder axis. The swift clothing, possibly together with the card flat rods distributed over the cylindrical surface of the swift, aligns and cleans the supplied textile fibers during rotation of the swift. After this aligning and cleaning operation, the fiber fleece obtained in this way is removed from the swift by means of a so-called doffer and/or doffing cylinder and transported to further processing stations. The doffers and/or doffing cylinders usually also have all-steel sawtooth clothing in the area of their cylindrical surface, which, in the course of rotation of the doffer and/or doffing cylinder, engages the fiber fleece that is entrained by the swift or a doffing cylinder and removes it from the swift or the doffing cylinder.
Particularly in the processing of especially fine-denier fibers of natural or synthetic polymers, it has been found that the transfer of the fiber fleece from the swift to the doffer or doffing cylinder presents problems. This causes the swift clothing to become filled with fiber material that has not been removed, which causes unsatisfactory alignment and cleaning of the supplied textile fibers by the swift.
Moreover, it was found that the fiber fleece removed by the doffing cylinder, particularly in the case of higher production weights, is prematurely removed from the doffer or doffing cylinder, and this can result in problems during further processing of the fiber material.
To eliminate these problems, it has already been suggested that the sawteeth of the all-steel sawtooth clothing of the doffer or doffing cylinder be provided with lateral rolled groove arrangements. It was found, however, that, especially in high-capacity carding machines with production capacities of 80 kg or more, at the high peripheral speeds of the doffer or doffing cylinder necessary to maintain this production capacity, premature detachment of the fiber fleece from the doffer or doffing cylinder occurs. This occurs despite the rolled groove arrangements, which promote greater adhesion.
To solve this problem, DE 100 12 561 proposes a modification of the well-known sawtooth wires, in which, in addition to the rolled groove arrangement, profiling of the tooth backs of the sawteeth is provided. In the profiling, at least one tooth has a convex segment that passes over into a concave segment in the direction of the tooth bottom. In the sawtooth wires described in the cited document, this profiling can be designed both in the form of recesses and in the form of projections in the region of the tooth backs. With sawtooth wires of this type, an adhesive force can be made available that is sufficient even for the operation of high-capacity carding machines. Of course, especially in the processing of synthetic fibers with a fineness of 0.8-40 dtex, especially silicone-treated synthetic fibers, and in the processing of fine wool, it was found to be a problem that a satisfactory yarn quality cannot be achieved with the sawtooth wires described in DE 100 12 561 at high production speeds.